KiTTY 0.84.1.55-beta

KiTTY 0.84.1.55-beta

One headline feature: automatic font fallback for characters your terminal font does not have - Nerd Font icons, CJK, box drawing and symbols now render without switching fonts.

Highlights:

• Missing-glyph font fallback, ported from upstream PR cyd01#555 by blreay - thanks! When the terminal font is missing a character, KiTTY probes a list of fallback fonts and draws that character from the first font that has it. Cell widths are unchanged; only the glyph's source font differs. This covers what Windows' own font linking cannot, notably private-use-area icons (Nerd Fonts / Powerline prompts).
• Configured in a new kitty.ini [FontFallback] section (see docs/KITTY-INI.md): active master switch (default yes), fallback= comma-separated font list tried before the built-in defaults (leading ! replaces them), override=U+range:Font pinning, and log/logfile for troubleshooting. The built-in fallback list leads with Cascadia Mono/Code and the Segoe UI symbol fonts, then the major CJK UI fonts.
• Limitations: rendering is plain GDI, so emoji drawn via fallback come out monochrome; supplementary-plane emoji may need an explicit override= range; with a raster primary font (Terminal/Fixedsys) the feature disables itself. active=no turns it off entirely.
• The port also fixes two issues in the original module: a raster primary font no longer sends all text to the first fallback font, and very long mixed-font lines are no longer truncated at 64 runs.
• Internals: the configuration self-test (test_conf) now expects KiTTY's defaults for ProxyLogToTerm and ShiftedArrowKeys - the two remaining failures dating from the 0.84 baseline import - so the suite runs green and serves as a regression gate for future upstream rebases.

Known issues and limitations (tag-pinned):
https://github.com/hknet/KiTTY/blob/kitty-0.84.1.55-beta/KNOWN-ISSUES.md